Beta Marine Beta 28 Operator's Maintenance Manual page 15

WATERLOCK / SILENCER
You must always fit a waterlock / silencer to stop any
water in the exhaust system back filling the engine. The
water lock should always be fitted at least 30 cms away
from the injection bend and at least 30 cms below the
14 Waterlock / Silencer Positioning
You should always create a 'gooseneck' with the exhaust
hose (or purchase a propriety one) by raising the exhaust
hose 40 cms above the waterline before exiting the
transom at least 5 cms above the waterline. This will stop
any waves pushing seawater down the exhaust.
IMPORTANT!
If measurement 'H' cannot be met, a high rise exhaust
injection bend must be installed. Residual water must
flow to waterlock / silencer or overboard.
15 Exhaust Hose 'Gooseneck'
16 Exhaust 'Gooseneck'
injection bend, being as low as reasonably possible, so
that all the water can drain down into it. The waterlock
should have sufficient capacity to hold an exhaust system
full of water - draining into it.
L
H
Position of silencer in relation to exhaust hose length:
Length (L)
30 cm
120 cm
With longer lengths of exhaust hose you may need to
support the hose to avoid a drooping hose and water
build up.
40 cm
13
Height (H)
30 cm
40 cm